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31.
[reaction: see text] The temperature dependence of the dissociation of dimers formed from highly stabilized carbon-centered radicals has been examined. Analysis of the data yields the bond dissociation energy (BDE) for the central head-to-head C-C bond in these compounds. For example, for the dimer derived from 3-phenyl-2-coumaranone, BDE is 23.6 kcal/mol and the C-C bond length 1.596 A, a rather long value for a sigma bond. 相似文献
32.
A
cha Ali-Bey Hasna Fatiha Loukil Gilles Gosselin Andr Mathieu Abderrezzak Mesli 《Journal of heterocyclic chemistry》1982,19(3):617-624
Hydrolysis of the imine function of a series of Schiff bases derived from pyrrole-2-carboxaldehyde and substituted anilines (X = H, p-OCH3, p-OC2H5, p-CH3, p-Cl, p-Br, m-CN, m-NO2, p-NO2) was studied in all of the pH ranges. The hydrolysis curves log kabs (mn?1) = f(pH) were established in buffered aqueous methanol by polarography or amperometry. The shapes of the curves obtained for pH > 5 indicates that N-pyrrolylmethylene-2 anilines hydrolyse according to the same mechanism as N-benzylidene anilines. The particular stability of these products for pH < 5 permits one to obtain complete hydrolysis curves in acid media. A very good Hammett correlation (kobs = + 1,73) has been established from the maxima which appear for strong acidity. This stability is interpreted as due to the specific electron-donating effect of the pyrrole nucleus. The influence of the structural parameter X on the morphology of the curves log kabs = f(pH) and on the hydrolysis mechanism of the imine function is discussed in all of the pH ranges. 相似文献
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Iron-catalyzed homo-coupling of simple and functionalized arylmagnesium reagents is described. The reaction is highly chemoselective (CN, COOEt and NO(2) groups are tolerated). The procedure was used to perform intramolecular couplings. This cyclization reaction is the key step of the total synthesis of the N-methylcrinasiadine. 相似文献
35.
The synthesis of a new series of stable and soluble EDOT oligomers end-capped with n-hexyl groups is described. Optical and electrochemical results indicate that the synergy between the direct electron-releasing effects of the ethylenedioxy groups and the self-rigidification resulting from intramolecular interactions controls to a large extent the HOMO-LUMO gap. 相似文献
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Chakravarthi Simhadri Liting Bi Mathieu L. Lepage Mahdi Takaffoli Zhipeng Pei Stefania F. Musolino Abbas S. Milani Gino A. DiLabio Jeremy E. Wulff 《Chemical science》2021,12(11):4147
Motivated by a desire to develop flexible covalent adhesives that afford some of the same malleability in the adhesive layer as traditional polymer-based adhesives, we designed and synthesized two flexible, highly fluorinated bis-diazirines. Both molecules are shown to function as effective crosslinkers for polymer materials, and to act as strong adhesives when painted between two polymer objects of low surface energy, prior to thermal activation. Data obtained from lap-shear experiments suggests that greater molecular flexibility is correlated with improved mechanical compliance in the adhesive layer.Flexible, highly fluorinated covalent adhesives are synthesized, and are shown to afford comparable C–H insertion efficiency and adhesion strength relative to a rigid analogue, while providing improved mechanical compliance in the adhesion layer. 相似文献
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Trombotto S Danel M Fitremann J Bouchu A Queneau Y 《The Journal of organic chemistry》2003,68(17):6672-6678
The base-catalyzed reaction of carboxymethyl 3,4,6-tri-O-acetyl-alpha-D-glucopyranoside 2-O-lactone (prepared from isomaltulose) with amino acids and fatty amines under basic catalysis gave a series of new pseudoglucopeptides, nonionic amphiphiles, and polymerizable derivatives. The same reaction applied to alcohols provided the corresponding 2-(alpha-D-glucopyranosyloxy)acetyl esters with either basic or acidic catalysts. 相似文献